Spirit Copes With Decreasing Solar Energy

Jul 07, 2006

With electrical power from Spirit's solar array down to about 300 watt-hours per Martian day, or sol, the science team is able to plan only one major activity per sol and often needs to devote one sol to recharging the rover's batteries.

A hundred watt-hours is the amount of electricity needed to light one 100-watt bulb for one hour. Spirit remains healthy and continues to make progress on the winter science campaign.

Engineers successfully uploaded half of a new flight software upgrade and planned to take advantage of overflights by NASA's Odyssey orbiter to transmit more flight software files via UHF frequencies.

The rover team created a new technique for correcting drift (changes with time) in the rover's inertial measurement unit, which affects the pointing accuracy of the miniature thermal emission spectrometer.

The IMU provides roll, pitch, and yaw information to the rover. Typically, rover handlers minimize error by having the rover complete a sequence of steps known as a "get fine attitude" based on the changing position of the sun relative to the rover.

The rover then takes images with the hazard avoidance and navigation cameras, which provide guidance for positioning the robotic arm and driving as well as documenting the correction.

The entire process takes about one hour, which at present is roughly equivalent to a week of winter science operations. Between these updates, the rover's onboard computer keeps track of attitude changes, but error builds up in this calculation over time.

The new process involves sending a command to Spirit with the position reported by the rover after the last quick "get fine attitude," on sol 855 (May 30, 2006). Rover drivers confirmed that the rover had not moved since then by checking images from the hazard avoidance cameras.

Following the usual attitude adjustment, the team planned to direct the rover to take two new images with the navigation camera and compare those to images from sol 855 as an additional means of verifying the accuracy of the adjustment.

Sol-by-sol summaries

Sol 881 (June 25, 2006): Rover handlers spent one hour transmitting flight software files to Spirit via X-band frequencies using the rover's high-gain antenna.

Sol 882: Spirit completed a "bitty cloud" search designed to look for changes in the Martian sky, a photon transfer observation to measure electronic noise (unwanted signals) picked up by CCDs (charge-coupled devices -- imaging sensors that convert light into electrical current) in the left eye of the rover's panoramic camera, and observations of ground targets and atmosphere with the miniature thermal emission spectrometer.

Sol 883: Spirit conducted a 5-hour observation of the rock target "Halley" with the Mössbauer spectrometer. The rover also conducted morning atmospheric studies.

Sol 884: Spirit completed a photon transfer observation of the right eye of the panoramic camera.

Sol 885: Plans called for Spirit to conduct atmospheric studies of the Martian sky and ground using the panoramic camera and miniature thermal emission spectrometer. The rover's schedule also included another 5-hour study of Halley with the Mössbauer spectrometer.

Sol 886: Plans called for Spirit to conduct more "bitty cloud" observations, collect remote observations of the sky and ground with the miniature thermal emission spectrometer, set the rover attitude, and calibrate the high-gain antenna.

Sol 887: Plans called for Spirit to acquire a single frame of column 21 of the "McMurdo panorama."

Sol 888 (July 3, 2006): Plans called for Spirit to recharge the batteries and make morning atmospheric studies.

Odometry:

As of sol 884 (June 28, 2006), Spirit's total odometry remained at 6,876.18 meters (4.27 miles).

Copyright 2006 by Space Daily, Distributed United Press International

Explore further: Life on Mars? Implications of a newly discovered mineral-rich structure

add to favorites email to friend print save as pdf

Related Stories

In low gravity, scientists search for a way to saute

Aug 08, 2014

Chow mein on Mars? Moo shu on the moon? What would it be like to stir-fry in space? A bit messy, according to Cornell researchers, who recently conducted the first partial gravity cooking on record.

Curiosity spots a heavy metal meteorite

Jul 16, 2014

Talk about heavy metal! This shiny, lumpy rock spotted by NASA's Curiosity rover is likely made mostly of iron—and came from outer space! It's an iron meteorite, similar to ones found in years past by Curiosity's ...

Opportunity peers out from 'Pillinger Point'

Jun 17, 2014

NASA's decade old Opportunity rover has reached a long sought after region of aluminum-rich clay mineral outcrops at a new Endeavour crater ridge now "named 'Pillinger Point' after Colin Pillinger the Principal ...

NASA rover gains Martian vista from ridgeline

May 20, 2014

The rim surrounding Endeavour Crater on Mars recedes southward, then sweeps around to the east in a vista obtained by NASA's Mars Exploration Rover Opportunity. The view is from high on the south end of the ...

Against the current with lava flows

May 12, 2014

Primeval lava flows formed the massive canyons and gorge systems on Mars. Water, by contrast, was far too scarce on the red planet to have cut these gigantic valleys into the landscape. This is the conclusion ...

Recommended for you

Australian amateur Terry Lovejoy discovers new comet

9 hours ago

It's confirmed! Australian amateur astronomer Terry Lovejoy just discovered his fifth comet, C/2014 Q2 (Lovejoy). He found it August 17th using a Celestron C8 fitted with a CCD camera at his roll-off roof ...

Students see world from station crew's point of view

Aug 19, 2014

NASA is helping students examine their home planet from space without ever leaving the ground, giving them a global perspective by going beyond a map attached to a sphere on a pedestal. The Sally Ride Earth ...

Mars deep down

Aug 19, 2014

Scarring the southern highlands of Mars is one of the Solar System's largest impact basins: Hellas, with a diameter of 2300 km and a depth of over 7 km.

User comments : 0